A field based study of swimbladder adjustment in a physostomous teleost fish

Kostas Ganias; Stella Michou; Cristina Nunes

doi:10.7717/peerj.892

A field based study of swimbladder adjustment in a physostomous teleost fish

PeerJ. 2015 Apr 9:3:e892. doi: 10.7717/peerj.892. eCollection 2015.

Authors

Kostas Ganias¹, Stella Michou¹, Cristina Nunes²

Affiliations

¹ School of Biology, Aristotle University of Thessaloniki , Thessaloniki , Greece.
² IPMA-Instituto Português do Mar e da Atmosfera , Lisboa, Avenida de Brasilia s/n , Portugal.

Abstract

The present study assesses swimbladder dynamics in natural occurring sardine, Sardina pilchardus, populations with the aim to examine whether this is affected by bathymetric positioning and the physiological state of the individuals. To do so, swimbladder size and shape were modeled in relation to catch depth and the size of various visceral compartments such as gonad, liver, fat and stomach. Swimbladder size was shown to be related to depth in a way that individuals with smaller swimbladders occurred at larger depths. Moreover, evidence is provided that the swimbladder in sardine might have a functional relationship both with the reproductive and the feeding state of individuals, since none of the fish with hydrated gonads and/or large stomachs displayed distended swimbladders.

Keywords: Atlantic sardine; Bathymetric distribution; Physostomous; Shape descriptors; Swimbladder size.

Grants and funding

The present work was operated within the framework of IPMA’s acoustic surveys funded by the Portuguese biological sampling programme integrated in the EU Data Collection Framework (DCF). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.